Change namespace for defaults controllers

To allow proper path prefix for view partials when using
config.action_view.prefix_partial_path_with_controller_namespace

test/controllers/default/units_controller_test.rb

@@ -0,0 +1,8 @@
+require "test_helper"
+
+class Default::UnitsControllerTest < ActionDispatch::IntegrationTest
+  test "should get index" do
+    get units_defaults_index_url
+    assert_response :success
+  end
+end